Any Mormons here? Trying to clarify some terms...(unit/ward/branch)

For anyone with knowledge of the LDS, can you please clarify the difference between a ward, a unit and a branch?

I'm in an area with three wards, I think, and a neighboring city has two, but the guy (a high councilor for something) instead kept referring to the 14 "units" in the area. Is this somewhat interchangeable? Like maybe a unit is a more general term for a ward or a branch?

Essentially, if I refer to these collectively, which term should I use?

(Story: LDS sending teams to volunteer in rebuild.)
Thank you. I didn't see "units" on the LDS site or Wiki, but that is definitely the word he kept using.